A TEMPERATURE-PROGRAMMED DESORPTION X-RAY PHOTOELECTRON-SPECTROSCOPY STUDY OF DITERTIARYBUTYLARSINE ON GAAS(100)

The adsorption of ditertiarybutylarsine [(t-Bu)2AsH] on GaAs(100) was studied using temperature-programmed desorption (TPD) and X-ray photoe lectron spectroscopy (XPS). In TPD, following adsorption at 120 K, thr ee (t-Bu)2AsH desorption peaks were observed. They are assigned to phy sically adsorbed (t-Bu)2AsH and two chemically absorbed states of (t-B u)2AsH. The highest temperature peak was observed to shift from 415 to 375 K with increasing coverage. Following saturation of this peak, a second desorption peak was observed at 230 K. Finally, the TPD peak fo r a physically adsorbed multilayer was observed at 170 K. No evidence for a beta-hydride elimination reaction of t-butyl ligands to isobuten e or irreversible decomposition of (t-Bu)2AsH was observed. XPS data f or both C and As can be deconvoluted to show two separate peaks, one a ttributed to physisorbed and the other to associatively chemisorbed (t -Bu)2AsH.